Field of the Invention
The present invention relates to a pressing load setting method of a tire testing machine in which one of a tire and a drum is pressed onto the other while rotating upper and lower spindles nipping the tire, and a pressing load applied to the tire is set to be a target value.
Description of the Related Art
Tire uniformity is measured by pressing one of a tire and a drum onto the other and rotating the tire in a state where a load is applied to the tire. At this time, the tire is pressed at a target load value according to a type of the tire.
JP 2013-124858 A discloses a pressing load setting method of tire uniformity measurement in which relative movement of a rotating body and a tire is precisely stopped at a target load value by using a dynamic longitudinal spring constant calculated for each tire to be supplied for the tire uniformity measurement. According to technique described in JP 2013-124858 A, a pressing load can be promptly set to be the target load value with high precision.
However, in JP 2013-124858 A, circumferential position matching of the tire is not performed at the time of calculating the dynamic longitudinal spring constant. Therefore, when the dynamic longitudinal spring constant of the tire is not uniform in the circumferential direction, an accurate dynamic longitudinal spring constant cannot be calculated.